LIFE TECHNOLOGIES LOSING DNA SEQUENCING EXPERT

Rothberg, who headed company’s Ion Torrent, resigns at Carlsbad firm

Jonathan Rothberg, developer of solid-state DNA sequencing regarded as Life Technologies’ future, has left the Carlsbad biomedical products company.

Life Tech said in a regulatory filing Wednesday that Rothberg had resigned “to pursue new opportunities.”

The company paid $375 million in 2010 to buy Ion Torrent, a business founded by Rothberg that had found a way to directly sequence DNA on computer chips. By taking advantage of the exponential increase in chip power known as Moore’s law, Ion Torrent said it could drastically reduce the cost of gene sequencing.

After the purchase, Rothberg stayed on with Life Tech, where he continued to head Ion Torrent. That division produces the Personal Genome Machine, which uses solid-state sequencing.

“As a founder of four genetics companies, his departure from Life Technologies to seek his next entrepreneurial challenge is a natural next step, and we appreciate the deep bench of talent that Jonathan has built over the past three years to guide the long-term success of Ion Torrent,” the Life Tech filing stated.

Reached for comment, Life Tech said it had nothing to add to what is in the filing.

Rothberg is the highest-profile executive to depart Life Tech since the company agreed in April to a $13.6 billion buyout by scientific instrumentation giant Thermo Fisher. Greg Lucier, Life Technologies’ chief executive, said he would continue to lead the company until the deal is complete, expected in early 2014.

Life Tech is the biggest biotech company in San Diego County, with a market value as of Wednesday of $12.7 billion.

The Ion Torrent approach is promising, but it is not yet equal to the light-based sequencing approach taken by its San Diego-based competitor Illumina, said Dr. Eric Topol, a geneticist who is chief academic officer of Scripps Health.

Ion Torrent chips contain microscopic liquid-filled wells that receive DNA samples. Each well is coated with a DNA template that reacts only with its complementary DNA “letter.” When sample and template match, it produces a detectable change in voltage. By moving to more powerful chips, speed can be increased geometrically.

Illumina uses a different reaction that reports the letters as different colors of light, and it is generally regarded as the most accurate, Topol said. Medical applications of DNA sequencing require virtually complete accuracy. But speed and accuracy aren’t exclusive; greater speed can be used to improve accuracy, by repeating scans. For a medical-grade genome, a scan must be run at least 30 times.

Topol said Life Tech has effective management to continue developing the Ion Torrent technology to reach its potential.

“(President and Chief Operating Officer) Mark Stevenson, who is running the company, is an exceptional leader, and they know where to take the chip sequencing, with respect to much higher-density chips, much lower cost and higher accuracy,” Topol said. “I’m confident they’ll get there eventually.”

Rothberg has been replaced by Ronnie Andrews as head of the Ion Torrent business. Andrews will remain in charge of the company’s Genetic & Medical Sciences group, which includes Ion Torrent. That group was formed in April.